Priority is claimed to Patent Application Number 2000-71236, filed in the Republic of Korea on Nov. 28, 2000, herein incorporated by reference.
1. Field of the Invention
The present invention relates to a magnetic head for writing/reading a magnetic signal on/from a recording medium, and more particularly, to a magnetic head constructed so as not to generate magnetic concentration due to external magnetic field.
2. Description of the Related Art
An apparatus for writing/reading a magnetic signal on/from a recording medium, e.g., a hard disk drive, includes a magnetic head for writing and reading information. A magnetic head 10, as shown in FIG. 1, is installed in a slider 20 provided at one end of a swing arm 30, and moves to a track being at a desired position on a recording medium (not shown) by rotation of the swing arm 30 to perform a write or read operation.
FIG. 2 is an enlarged view of the magnetic head 10 shown in FIG. 1 As shown in FIG. 2, the magnetic head 10 includes a magneto-resistive head 14 for reading information and an inductive write head for writing information. The magneto-resistive head 14 reads a magnetic signal written on a recording medium, and the inductive write head including a top pole 11 and a bottom pole 12 for producing a leakage flux passing through the recording layer of the recording medium, and a write coil 13 used as a current supply route, writes given information on a recording medium.
The inductive write head affects the quality of a signal written on a recording medium. That is, if inputting by the inductive write head is not clearly performed, reproduction cannot be satisfactorily performed even if the performance of the magneto-resistive head 14 is excellent. In particular, the inductive write head is very sensitive to an external magnetic field. For example, if a magnetic stray field generated from a voice coil motor (VCM) for driving the swing arm is concentrated by the inductive write head. This is called an antenna effect, in which information is erroneously written on or erased from a recording medium by the external magnetic field concentrating in the inductive write head.
FIGS. 3A and 3B show the distribution of a magnetic flux induced to an inductive write head and a recording medium by an antenna effect arising due to an external magnetic field.
As shown in FIGS. 3A and 3B, a magnetic field generated from an external magnetic field generating source 1 by an antenna effect extends toward top and bottom poles 11 and 12 of an inductive write head. A soft magnetic layer 3 is formed under a recording layer 2 of a recording medium. In this case, magnetic concentration occurs at the top and bottom poles 11 and 12 of the inductive write head. In particular, as shown in FIG. 3B, in view of configuration of the top pole 11, a width wxe2x80x2 of a portion positioned over the write coil 13 is much greater than a width w of a portion facing the recording layer 2. For example, in the case where the magnetic strength of a rear part of the top pole 11 is 100 Oe (oersted), the magnetic strength of an edge part corresponding to the recording layer 2 is 100xc3x97wxe2x80x2/w Oe. In other words, the magnetism at the edge part is strengthened in a proportion of wxe2x80x2/w. As described above, the external magnetic field concentrated by the top and bottom poles 11 and 12 affects the recording layer 2 by being strengthened at the edge part. In a vertical writing type magnetic head, erasure is first performed by a bottom pole and a write operation is then performed by a top pole. The external magnetic field is a stray field that undesirably causes erasure of information and a write operation of information. Major factors of the external magnetic field generating source 1 include a swing arm, which is a magnetic field generating source in an information recording apparatus and provides a magnetic circuit, and a VCM for driving the swing arm. The magnetic concentration due to the external magnetic field is disadvantageous for a high-density information recording system.
To solve the above-described problems, it is an object of the present invention to provide a magnetic head which can effectively suppress a magnetic concentration due to an external magnetic field.
It is another object of the present invention to provide a magnetic head which can effectively write and erase erroneous information by suppressing concentration of an external magnetic field.
To accomplish the above objects, there is provided a magnetic head including a bottom pole, a top pole spaced a predetermined distance apart from the bottom pole, an inductive write coil for forming a magnetic field at the bottom and top poles, and a magnetic shield layer which is positioned over the top pole and whose the leading edge is aligned with the leading edge of the top pole.
According to an embodiment of the present invention, the width of the magnetic shield layer is wider than the width of the top pole. Also, an intermediate layer is preferably interposed between the edges of the magnetic shield layer and of the top pole opposite to the edge intended to be adjacent to the recording media, and the intermediate layer is preferably made of a magnetic material. Further, a magneto-resistive head is positioned under the bottom pole.